multiwire branch circuits

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JdoubleU

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I remember as a apprentice working on a school pull wire for outlets from a 3 phase panel. It was in most cases Blk, red, blue shareing a neutral. When makeing up the panel, I don't recall ever useing 3pole breaker so that you can disconnect all outlets simultaneously as the code requires according to 210.4. Could someone explain why you don't see that on 3phase panels in a school serving outlets.
 
You need a multi-pole breaker only if more than one of the circuits are on the same yoke or piece of equipment. 210.4(B).
 
480sparky said:
You need a multi-pole breaker only if more than one of the circuits are on the same yoke or piece of equipment. 210.4(B).
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You're right for '05
You're wrong for '08

Same yoke spec is gone for '08. . All MWBC need multipole breakers or handleties.

David
 
dnem said:
You're right for '05
You're wrong for '08

Same yoke spec is gone for '08. . All MWBC need multipole breakers or handleties.

David
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Is there an approved handle tie for three breakers?

For a four wire multiwire circuit wouldn't it require a three pole breaker?
 
jwelectric said:
Is there an approved handle tie for three breakers?
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Approved is according to the listing from the breaker manufacturer. . They decide what's allowed to be used on their breaker.

jwelectric said:
For a four wire multiwire circuit wouldn't it require a three pole breaker?
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..... or handle ties on the singles
 
jwelectric said:
Is there an approved handle tie for three breakers?

For a four wire multiwire circuit wouldn't it require a three pole breaker?
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My supplies say there are no listed handle ties for 3 pole breakers but they have been wrong before. Ge and Siemens anyway.
 
Square D makes handle ties for their QO and QOB style anyway. I'm not sure about their bigger breakers(480/277).
 
electricman2 said:
Another crazy rule. I have to de-energise 3 circuits to work on one:-? .
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On the contrary, that's exactly the intention. There will be two circuits' worth of equipment you won't damage by jostling a still-carrying-current shared-neutral connection, not to mention yourself.
 
LarryFine said:
On the contrary, that's exactly the intention. There will be two circuits' worth of equipment you won't damage by jostling a still-carrying-current shared-neutral connection, not to mention yourself.
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Larry, you have enough knowledge to be able to work on one part of a MWBC without smoking other parts. Only qualified people should be digging that far into an electrical system. I think the new rule stinks.
 
dnem said:
Approved is according to the listing from the breaker manufacturer. . They decide what's allowed to be used on their breaker...... or handle ties on the singles
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C3PO said:
Square D makes handle ties for their QO and QOB style anyway. I'm not sure about their bigger breakers(480/277).
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I don?t think that you will be able to find handle ties for three pole breakers. Two yes, three no.
 
For these MWBC's where you don't want turn off all the circuits to work on one, simply install single pole switches for each circuit immediately after leaving the panelboard, this way you have met the code requirement and can still isolate the individual phases or legs downstream with out turning them all off. ;) :)


Roger
 
I don't know of any manufacture offering handle ties for tieing three single pole breakers together either.

C3PO, do you have a model number for the SQ D breakers?

Roger
 
I think, from past posts, that most people here think the new rule stinks, however, there are a very vocal minority that think it's a good rule.

Let's start a poll and find out if I'm right or wrong.

A vocal minority post should follow this one...
 
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